1. Field of Invention
The invention relates to a process for downloading data intended for updating appliances or for giving the appliances new functions, the data being dispatched by a communication center.
The invention applies more especially to the sending of programs to be downloaded into the memory of appliances which are typically television video decoder receivers.
2. Description of Related Art
These appliances, which hereinbelow will be referred to more simply as “decoders”, receive signals broadcast by a satellite or a hertzian network or an optical cable (coaxial or optical). The mode of transmission by the broadcasting network is unidirectional. The signals broadcast represent pictures and sound destined for the television and digital information destined for the decoders. The broadcasting network consists of several broadcasting channels. A channel is a means of acquiring information continuously through a means of communication. For an analog television, the channels are frequency bands allotted to the broadcasting of a station. In this case, the digital information is broadcast during the frame flyback or “VBI”. For a digital television, the channels are data streams having the same program identifier, a second level of identification makes it possible to distinguish the audio-visual data from the digital information. This information constitutes interactive services, teletext or else data for updating the software of the decoder, etc.
A decoder comprises a central unit which executes software stored in a read-only memory and/or in a nonvolatile programmable memory. It is generally furnished with an interface for bidirectional dialog, more commonly referred to as a “return path”, which makes it possible to establish a specific link with the communication center. This interface is typically a modem linked to the switched network.
The information received by the broadcasting network is in particular the update data, the latter making it possible to upgrade the functionalities of the decoder. They are stored in the programmable memory. The automatic downloading of the update data performed during an update campaign avoids the need for manual interventions by the user on the decoder. These data are sent repetitively during sessions.
The main function of a decoder is to offer the user pictures and interactive services. The downloading of the update data is a secondary and hence nonpriority task. The resources of a decoder do not necessarily make it possible to manage both interactive services and the downloading of update data. It is therefore necessary to find a solution that makes it possible to perform downloading while inconveniencing the user as little as possible. The systematic downloading of the data via the return path cannot be envisaged since it generally has a more limited bandwidth than that of the broadcasting network and the use of a leased line costs money. The invention proposes a flexible way of downloading update data by tailoring the resources of the decoder so as to inconvenience the user as little as possible.